Name three intermolecular forces that stabilize the structure of DNA, and explain how they act. A. flat, N-containing bases stack above each other, forming ion-dipole bonds to aqueous surroundings B. nitrogen bases form hydrogen bonds to their complementary bases C. sugar-phosphate chains form ion-dipole and hydrogen bonds to the aqueous surroundings D. sugar-phosphate chains form ion-dipole and hydrogen bonds to the nitrogen bases E. flat, N-containing bases stack above each other, forming intrachain hydrogen bonds F. sugar-phosphate chains form hydrogen bonds to the nitrogen bases G. nitrogen bases interact with their complementary bases through dispersion forces H. nitrogen bases form ion-dipole bonds to their complementary bases I. flat, N-containing bases stack above each other, allowing for interaction through dispersion forces J. sugar-phosphate chains stack above each other, allowing for interaction through dispersion forces

B. nitrogen bases form hydrogen bonds to their complementary bases

C. sugar-phosphate chains form ion-dipole and hydrogen bonds to the aqueous surroundings

J. sugar-phosphate chains stack above each other, allowing for interaction through dispersion forces

Explanation:

B) The hydrogen bonding between complementary base pairs is such that the most energetically stable DNA configuration is achieved when adenine pairs with thymine and guanine pairs with cytosine. Thus although the spatial requirements of B-DNA potentially allow four complementary base pairs to be formed (i. e., G-T, G-C, A-T, and A-C), only the G-C and A-T base pairs are normally found in DNA.

C) The basic structure of DNA can be divided into two portions: the external sugar-phosphate backbone, and the internal bases. The sugar-phosphate backbone, as its name implies, is the major structural component of the DNA molecule. The backbone is constructed from alternating ribose sugar and phosphate molecules which are highly polar. Because the backbone is polar, it is hydrophillic which means that it likes to be immersed in water.

J. The anionic phosphate groups interact electrostatically with each other, and through ion-pi interactions with the aromatic ring sugars and nucleobases. When a guanidinium cation is present, the anionic phosphate group has been reduced to a dipole, and the tuning of denticity tunes the dipole magnitude and orientation. The electrostatic ion-ion interactions of the phosphate groups are reduced to ion-dipole interactions, and the interactions with the aromatic sugars and nucleobases are likewise modified to have a larger contribution from non-electrostatic London dispersion forces